Implies that the speaker is sending secret or whispered information to another person
Psst, John, don’t tell anyone, but I’ve got lots of candy stashed away.
Psst is a sound that someone makes when they want to attract another person's attention secretly or quietly. `Psst! Come over here!' one youth hissed furtively. Used to capture someone's attention inconspicuously. a sound people make when they want to attract someone's attention without other people noticing (Natural sound)